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Monday, October 26, 2015

Significant local aurochs admixture in modern British and Irish cattle

Open access at Genome Biology:

Background: Domestication of the now-extinct wild aurochs, Bos primigenius, gave rise to the two major domestic extant cattle taxa, B. taurus and B. indicus. While previous genetic studies have shed some light on the evolutionary relationships between European aurochs and modern cattle, important questions remain unanswered, including the phylogenetic status of aurochs, whether gene flow from aurochs into early domestic populations occurred, and which genomic regions were subject to selection processes during and after domestication. Here, we address these questions using whole-genome sequencing data generated from an approximately 6,750-year-old British aurochs bone and genome sequence data from 81 additional cattle plus genome-wide single nucleotide polymorphism data from a diverse panel of 1,225 modern animals.

Results: Phylogenomic analyses place the aurochs as a distinct outgroup to the domestic B. taurus lineage, supporting the predominant Near Eastern origin of European cattle. Conversely, traditional British and Irish breeds share more genetic variants with this aurochs specimen than other European populations, supporting localized gene flow from aurochs into the ancestors of modern British and Irish cattle, perhaps through purposeful restocking by early herders in Britain. Finally, the functions of genes showing evidence for positive selection in B. taurus are enriched for neurobiology, growth, metabolism and immunobiology, suggesting that these biological processes have been important in the domestication of cattle.

Conclusions: This work provides important new information regarding the origins and functional evolution of modern cattle, revealing that the interface between early European domestic populations and wild aurochs was significantly more complex than previously thought.

Very interesting paper, thanks for sharing. The ancient British cattle breeds (Highland, Dexter, Kerry, Welsh Black, White Park) probably also share higher levels of Auroch admixture with ancient Iberian cattle breeds, which appear not to have been typed for this paper. Cattle were probably introduced to the British Isles with megalithic culture. Also interesting to note the Zebu admixture in the Italian breeds. I vaguely remember a similar claim about Jersey/Guernsey (Channel Islands) cattle but I can't remember the souce. They look similar to Brown Swiss cattle.

I'd like to know if the native British Isles cattle had the change that resulted in a mutation of the beta casein protein string in milk. This results, as I've read, in formation during digestion, because of a weaker link along the chain, of peptides of casomorphins that act as opiods. A recent LA Times article mentioned it in a "cheese is really addicting" or some such, article. There are other possibly unhealthy results from it though, including GI immuno suppression and hypothesized links to diseases. This is speculative and has its proponents and detractors. The mutation seems to be more prominent among Holstein and Friesian cattle, that are often used in the dairy industry because of their large milk production. Jerseys and Guernseys have a much higher percentage of the ancestral. I was wondering about native breeds.

There was a paper on ancient pig DNA (basically mtDNA) that mentioned that LBK brought their own pigs as the oldest known pig remains in LBK sites show clear relation to the Levant. Mind you, there never were very much pigs remains at LBK sites. Ertebolla (almost certainly a HG continuity culture) sites' oldest pig remains also show affinity with the Levant but very quickly the remains show only local affinity. After a while the remains in LBK sites show local affinity as well.

LBK had far more cattle and sheep remains, but Ertebolla (And PWC in Gotland as well) had only pigs. This gives me the impression that they copied the idea of domestication from LBK and successfully adapted to it. It also suggest trade of life pigs.

Mind you, these kinds of studies are far more relevant for us than the number of reactions suggest. Has the high local aurochs admixture in Scottish cattle anything to do with the high WHG rate in Highlander Scots themselves? Pig remains, as I mentioned above, do show such a correlation, if not entirely lineair.

Well, like the author of the article made very clear, we don´t know yet about the DNA results from all the other aurochs samples (this is a bit like the WHG component and the over generalized assumptions that are based on it). This is was just one individual found in Great Britain.

Some Iberian and Italian aurochs, for example, had mtDNA T, which is certainly different from P, like this British aurochs had.

But this study is surely interesting, IMO, mostly in the sense that it demonstrates that British aurochs had a role on the formation of some local ancient landraces.

So apart from the UK case, it have been found aurochs admixture in Iberian, Italian, Korean and possibly also some Balkan breeds. We just don´t know if there´s direct evidence that it was due to respective local aurochs introgression or to cattle with aurochs influence coming from an entirely different country. It seems that at least, for the bull aurochs input, some local contact is very likely. Regarding the aurochs cow, is not that easy, since it was way more difficult to acquire it (some Italian, Portuguese and Korean breeds, seem to have aurochs cow influence, I just don´t know if it was the case for Great Britain and the Balkans). Bull aurochs, on the other hand, just jump the fence, cover the domestic cows and leave the offspring there. That may explain why bull aurochs had a much greater impact on modern breeds. Some african breeds also have admixture from the african bull aurochs. We don´t know yet if cows were also domesticated.